Police in have used truncheons and water cannon to break up a protest by opposition supporters in Azerbaijan who are complaining of vote fraud in an election earlier this month.
A reporter at the scene said he saw dozens of bloodied protesters after riot police moved in to disperse a crowd of about 10,000 people on a square in the outskirts of Baku.
Police said the protesters were breaking the law.
However, the violent scenes may create added discomfort for Ilham Aliyev, the president of the oil-producing state who is already facing Western criticism over the Nov. 6 parliamentary vote.
Police intervened after demonstrators, who demand the election results be overturned and a new vote held, refused to leave the square when the time the authorities had allocated for their rally ran out.
Most people ran away but sections of the crowd fought back with stones and wooden poles, leading to brief pitched battles in the streets surrounding the square.
Opposition parties have been holding frequent demonstrations since the election, which Western observers said was marred by ballot-rigging. The protests until now were peaceful.
The vote handed a big majority in parliament to supporters of President Aliyev, who succeeded his father Haydar in an election in 2003. That vote was also followed by violent clashes between police and opposition supporters.
Azerbaijan, a Muslim ex-Soviet state which borders Russia and Iran, supplies growing volumes of oil to world markets from its fields in the Caspian Sea.